Pneumatic air operated fastener driving apparatus



1968 D. VOLKMANN 3,397,828

PNEUMATIC AIR OPERATED FASTENER DRIVING APPARATUS Filed May 16, 1966 3Sheets-Sheet 1 o o D 5 I3 14 I 31 Fig.1 32 I NVENTOI? 0/575? VOLAMAlV/VAug. 20, 1968 D. VOLKMANN 3,397,823

PNEUMATIC AIR OPERATED FASTENER DRIVING APPARATUS Filed May 16, 1966 3Sheets-Sheet 2 Fig.2

INKS/V701? 0/5767? VOL/(MANN Aug. 20, 1968 D. VOLKMANN 3,397,828

PNEUMATIC AIR OPERATED FASTENER DRIVING APPARATUS Filed May 16, 1966 5Sheets-Sheet 5 76 x z'; A 78 8 33 Fig.3

l/VIENTO}? 0/5727? [WA/(MANN United States Patent 7 Claims. (Cl 227-130)ABSTRACT OF THE DISCLOSURE A pneumatic fastener driving' apparatus has apiston actuated clamping device for clamping a work piece before thefastener is driven into the work piece by a driving piston. To insure atwo-cycle system of operation, the cylinders for the two pistons areseparated by a partition and compressed air is supplied to the cylinderfor the clamping device actuating piston. A tubular guide is providedfor the actuating piston and extends through the partition. Compressedair is admitted to the tubular guide through an inlet port and flowsinto the cylinder for the driving piston only after the actuating pistonhas substantially completed its working stroke so as to uncover theinlet port 7 The present invention .relates to a pneumatic air operatedfastener driving apparatus by which staples and similar fastening meansare inserted into a work piece by -a driving piston in cooperation witha clamping device for the work piece which is in the shape of tongs andis connected with a second piston moving in reverse direction of thedriving piston and being also operated by compressed air. In a priorconstruction of a fastener driving apparatus both thesepistons areguided in one joint cylinder into which the compressed air. streams at apoint where it can act on the two pistons=in their theninoperativepositions in which their front surfaces are adjacent'to eachother. When the control valve of such construction is operated the airacts simultaneously on both pistons. Because of this, there is notsuflicient safeguard that the clamping device for the work piece isclosed before the driving piston starts its working stroke by which itcarries the fastening means from an ejection channel into the workpiece. This construction therefore does not provide the necessaryworking reliability of the apparatus.

It is an important object of the invention to provide'an apparatus inwhich the working stroke of the driving piston is not allowed to takeplace before the clamping device which is coupled with the secondpistonhas been actuated and has properly arrestedthe work piece.

Another object of the invention is to provide means for a portableapparatus which'do'not release the downward motion of the driving pistonfor driving the fastener into the workpiece before the second piston hasactuated the clamping device for'the workpiece.

A specific object of the invention consists in providing a pneumatic airoperated apparatus with a driving piston and an actuating piston for theclamping device in which both pistons are coaxial with each other andpermit an easy operation of the apparatus.

In accordance with these and many other objects the invention comprisesa pneumatic air operated apparatus for driving staples and otherfasteners into a workpiece in which an actuating piston for a clampingdevice of the workpiece is connected with this device and reversibly ofthe driving piston guided in a joint cylinder of the body of theapparatus. The air admission channel coming 3,397,828 Patented Aug. 20,1968 from a control valve is arranged above a partition separating theworking spaces of the driving piston and of the actuating piston for theclamping device from each other and being intersected by a channelconnecting the two working spaces with each other. This channel issurrounded by the actuating piston for the clamping device and onlyadmits compressed air to the working space of the driving piston afterthe actuating piston for the clamping device has fully or partlycompleted its working stroke.

A construction of the apparatus in this manner renders it possible thatthe actuating piston is made to close the clamping device for theworkpiece before the compressed air moves the driving piston by whichthe fastener is driven into the workpiece. The workpiece is thereforereliably mounted at the time the driving piston thrusts the fastenerfrom the ejection channel into the workpiece. The apparatus safely worksaccording to the two-cycle principle and because of the coaxialarrangement of driving piston and actuating piston it can be easilyhandled. The handle piece of the body of the apparatus is in accordancewith the usual practice situated in immediate neighbourhood of thecentral axis of the cylinder and its coaxial ejection channel. Theapparatus can be used in the same Way as a fastener driving apparatuswithout the clamping device for the workpiece.

Further advantages and features of the invention including details ofconstruction and combinations of parts will be more particularlydescribed with reference to the accompanying drawings. In the drawings:

FIGURE 1 is a lateral view, partly in section, of an embodiment of thecomplete apparatus according to the invention;

FIGURE 2 is a partial longitudinal section of the driving part of theapparatu in its initial position;

FIGURE 3 is a partial longitudinal section of the driving part of theapparatus in the terminal position of the actuating piston for theclamping device.

With reference to FIGURE 1, the apparatus has a body 1 which may consistof a light metal cast the rear portion of which has the shape of ahandle piece 2 and is provided with an extension 3 for connection to acompressed air supply pipe. Handle piece 2 surrounds a compressed airstorage chamber 4 connected to which is via an entrance valve 6, whichis operated by a finger lever 5, a compressed air channel 7. The channel7 ends in a cylindrical casing 8 which is provided in the front portionof the body 1 of the apparatus and is in FIGURES 2 and 3 shown in alarger sectional view. Inserted in casing 8 is a guiding sleeve 9 forthe driving piston 10, which via a resilient intermediary piece 11,which may consist of a plastic material or a similar substance, isconnected with a driver 12 guided within the ejection channel 14. Thelatter is in the usual manner connected with a staple magazine 13.Driving piston 10 is also under the stress of a coil spring 15 whichreturns it into its initial position as shown in FIGURE 2. when it hascompleted its working stroke.

Below the point where the compressed air channel 7 ends in thecylindrical casing 8 the latter is provided with a partition 16, whichis provided with passages 18 sealed by check valve balls 17. Sunk intopartition 16 in the central axis of the cylindrical casing 8 is anupwardly extending tube 19 the upper portion of which has a radial bore20. Tube 19 extends into a cylindrical bore 21 of a bolt 22 which iscoaxial with tube 19. The lower end of bolt 22 carries a piston 23 whichis tightly guided within a cylindrical sleeve 25 inserted into casing 8and connected with it by threads 24. The piston 23 is under the pressureof a coil spring 26 which is fastened to its upper surface. The counterbearing for spring 26 is formed by a cap 27 which seals the cylindricalsleeve 25 and'has a vent 28.

As shown in FIGURE 1, a rod 29 is linked to the upper end of the bolt 22on which the piston 23 is carried and forms an articulated connectionwith tongs 30 which can be turned around a pivot 31 arranged at the rearlower end of the body 1 of the apparatus and are used to hold aworkpiece 32 into which a staple is intended to be driven.

To avoid beating of the driving piston and piston 23 against partition16 when carrying out their respective back strokes, which could lead todamages of the partition 16, the driving piston 10 and the partition 16are at their respective upper sides provided with elastic bumpers 33 and34 respectively. Another annular elastic bumper 35 is situated at thelower side of cap 27 by which the cylindrical sleeve 25 is sealed.

The apparatus is operated in the following manner.

In the inoperative position all the movable parts are in the positionsshown in FIGURES 1 and 2 in which the driving piston 10 and the piston23 are adjacent to the rigid partition 16, with but the elastic bumpers33 and 34 being interposed between them.

To release a Working stroke the entrance valve 6 for the compressed airis opened by actuating the finger lever 5, which causes compressed airto stream from the storage chamber 4 through channel 7 into the space 36above the partition 16. The compressed air acts on the part of theannular surface of piston 23 which projects over the bumper 34 and liftspiston 23 into the position shown in FIGURE 3, and piston 23 at the sametime collapses the spring 26. The upward motion of piston 23 causes thebar 29 to close the tongs 30 which thus arrest the workpiece 32. Whenthe piston 23 or the wall of the bolt 22 by which the piston 23 iscarried has passed the radial bore of tube 19 the compressed air isallowed to stream through this bore 20 and tube 19 into the space belowpartition 16 and to act on the part of the annular surface of thedriving piston 10 projecting over the bumper 33, whereupon the driver 12is moved in downward direction and a staple is issued from the magazine13 and driven into the workpiece 32. No compressed air can stream intothe space below partition 16 before the bore 20 is uncovered by piston23 since the passages 18 are blocked by the valve balls 17. Thisconstruction insures that the compressed air does not act on the drivingpiston 10 and thus relase its working stroke before the piston 23 hascompleted the major part of its travel and has closed the tongs 30.

When driving piston 10 and piston 23 have reached their respectiveterminal positions they are by the springs 15 and 26 returned into theirrespective initial positions as shown in FIGURE 2 since the compressedair admission valve 6 is then locked and no compressed air can thereforestream into the channel 7. The air upwardly displaced by driving piston10 is vented into the atmosphere through the now open passages 18 andthe compressed air channel 7 via a suitable channel of the compressedair admission channel. The air above piston 23 leaves through the vent28 of cap 27.

The apparatus operates in a distinct two-cycle system and reliably keepsthe workpiece 32 arrested within the tongs 30 before the driving piston10 starts its working stroke and drives the staple into it. The staplesof other fasteners are therefore always properly driven into theworkpiece. In the inoperative position of the apparatus the workpiececan be easily taken out of the tongs 30 as they will have released it oncompletion of the working stroke of the driver.

Although the present invention has been described in conjunction withone embodiment thereof it is obvious that those skilled in the art may"devise other embo'diments and combinations of parts which will fallwithin the scope of my appended claims.

What I claim is:

1. An apparatus for driving fastening means into a work piece comprisinga cylinder, a driving piston reciprocably guided within said cylinderfor driving the fasten ing means into the workpiece, an actuating pistonfor a clamping device, said actuating piston also being reciprocablyguided within said cylinder for movement opposite to said drivingpiston, a rigid partition. for separation of the Working spaces of saiddriving piston and actuating piston from each other, a compressed airpipe ending in said cylinder above said partition and in the workingspace of said actuating piston, and means defining an axial channelinterconnecting both said working spaces, said channel intersecting saidpartition and allowing admittance of compressed air to the working spaceof said driving piston not before said actuating piston has completedits working travel.

2. An'apparatus as described in claim 1 in which the actuating piston isof annular shape and is guided on a tube arranged in said partition inthe central axis of the cylinder, said tube having an opening which onbeing uncovered by the actuating piston, allows compressed air to streamfrom the working space of the actuating piston.

into the working space of the driving piston.

3. An apparatus as described in claim 2 in which said opening of thetube has a distance from the rigid partition which equals the major partof the working travel of said actuating piston.

1 4. An apparatus in accordance with claim 2 in which said actuatingpiston is fastened to the lower end of a bolt which is provided with anaxial bore, in which said tube is inserted and is through a rod coupledwith a clamping device. 7

5. An apparatus in accordance with claim 1 inwhich said partition isprovided with passage means for venting the working space of the drivingpiston and said passage means are sealed by check valve means.

6. An apparatus in accordance with claim 1 in which elastic bumpers arearranged between said rigid partion and the driving piston and actuatingpiston respectively, said bumpers being of smaller diameter than theirrespective pertinent pistons.

7. In a fastener driving apparatus having a driving piston movable in afirst cylinder portion for driving a fastener into a workpiece. and anactuating piston movable in a second cylinder portion for actuating aworkpiece clamping device, the improvement which comprises a partitionbetween said cylinder portions, means for introducing compressed airinto said second cylinder portion at one side of said partition, and airpassage means extending through said partition to the opposite sidethereof for connecting said cylinder portions, said air passage meansbeing operable to admit compressed air from said second cylinder portionto said first cylinder portion only after said actuating piston hassubstantially completed its working stroke for actuating the clampingdevice.

References Cited UNITED STATES PATENTS 2,687,522 8/1954 Juilfs 2272,854,953 10/ 1958 Osborne 9l461 2,943,327 7/1960 Juilfs 2271303,051,135 8/1962 Smith 91-l89 PAUL E. MASLOUSKY, Primary Examiner.

